Description
The 3-D Plasma and Energetic Particle Analyzer investigation on WIND will
measure ions and electrons in the interplanetary medium with energies including
that of the solar wind and the energetic particle range. It will study the
particles upstream of the bow shock in the foreshock region and the transient
particles emitted by the Sun during solar particle events following solar
flares. This experiment will cover the gap between the energy ranges covered by
SWE and EPACT.
The 3-D PLASMA instrument consists of two sensor packages mounted on small

radial booms, and an electronics package mounted inside the spacecraft. One
boom-mounted sensor package contains an array of 6 double-ended semiconductor
telescopes, each with two or three closely sandwiched silicon detectors to
measure electrons and ions above 20 keV. One side of each telescope is covered
with a thin foil which absorbs ions below 400 keV. On the other side, the
incoming electrons below 400 keV are swept away by a magnet so that electrons
and ions are cleanly separated. Higher energy electrons (up to ~1 MeV) and ions
(up to 11 MeV) are identified by the two double-ended telescopes which have a
third detector. The first sensor package also contains a pair of ion
electrostatic analyzers (PESA-L and -H) for measuring ion fluxes from ~3 eV to
40 keV. The second sensor package contains a pair of electron electrostatic
analyzers (EESA-L and -H) for measuring electron fluxes from ~3 eV to 30 keV,
and for making input (from EESA-H) to a fast particle correlator (FPC). The
FPC, using also plasma wave data from WAVES as input, measures perturbations to
the electron distribution function and studies other wave-particle
interactions.
For more information, see: http://sprg.ssl.berkeley.edu/wind3dp/esahome.html